行为型模式--设计模式详解？

public interface Strategy {
    public int calc(int a, int b);
}


public class Main1012 {
    public static void main(String[] args) {
        Environment1012 environment1012 = new Environment1012(new AddStrategy());
        System.out.println(environment1012.calculate(1,2));
    }
}

public class Environment1012 {
    private Strategy strategy;

    Environment1012(Strategy strategy){
        this.strategy = strategy;
    }

    public int calculate(int a,int b){
        return strategy.calc(a,b);
    }
}

public class DeductionStrategy implements Strategy{

    @Override
    public int calc(int a, int b) {
        return a - b;
    }
}

public class AddStrategy implements Strategy{

    @Override
    public int calc(int a, int b) {
        return a + b;
    }
}

public static void main(String[] args) {
        Dish cowAndTomato = new CowAndTomato();
        cowAndTomato.doDish();

    }

public class EggAndTomato extends Dish{

    @Override
    public void preparation() {
        System.out.println("准备鸡蛋和番茄");
    }

    @Override
    public void doing() {
        System.out.println("炒西红柿鸡蛋");
    }

    @Override
    public void client() {
        System.out.println("西红柿鸡蛋给客户端吃");
    }
}


public abstract class Dish {

    void doDish(){
        this.preparation();
        this.doing();
        this.client();
    }

    public abstract void preparation();

    public abstract void doing();

    public abstract void client();
}


public class CowAndTomato extends Dish{

    @Override
    public void preparation() {
        System.out.println("准备牛肉和番茄");
    }

    @Override
    public void doing() {
        System.out.println("炒番茄炖牛腩");
    }

    @Override
    public void client() {
        System.out.println("给客户端吃");
    }
}

    public static void main(String[] args) {
        WechatServer wechatServer = new WechatServer();
        Observer userZhang = new User("zhangsan");
        Observer userLi = new User("lisi");
        wechatServer.registerObserver(userZhang);
        wechatServer.registerObserver(userLi);
        wechatServer.setMsg("msg  one  one");

        wechatServer.removeObserver(userLi);
        wechatServer.setMsg("msg update ");
    }

public interface Observer {
    public void update(String msg);
}

public interface Subject {
    public void registerObserver(Observer observer);
    public void removeObserver(Observer observer);
    public void notifyObserver();
}

public class User implements Observer {
    private String name;
    private String msg;

    User(String name) {
        this.name = name;
    }

    @Override
    public void update(String msg) {
        this.msg = msg;
        read();
    }

    private void read() {
        System.out.println(this.name + "msg:" + this.msg);
    }


}


public class WechatServer implements Subject{

    private List<Observer> observerList;
    private String msg;

    public WechatServer(){
        observerList = Lists.newArrayList();
    }

    @Override
    public void registerObserver(Observer observer) {
        observerList.add(observer);
    }

    @Override
    public void removeObserver(Observer observer) {
        if(!CollectionUtils.isEmpty(observerList)){
            observerList.remove(observer);
        }
    }

    @Override
    public void notifyObserver() {
        for (Observer o: observerList) {
            o.update(this.msg);
        }
    }

    public void setMsg(String msg){
        this.msg = msg;
        notifyObserver();
    }
}